The present invention relates to a steel laminate gasket for an internal combustion engine, which can provide strong sealing pressure between two parts.
The steel laminate gasket of the invention can be used widely, such as a regular gasket situated between two engine blocks, cylinder head gasket and manifold gasket. Further, in the gasket of the present invention, cylinder holes Hc, water holes Hw, oil holes Ho and the like, as shown in FIG. 1, can be easily and securely sealed.
In the steel laminate gasket, one of the very important things when the steel laminate gasket is designed is how portions around holes of the engine are securely sealed. If the portions around the holes of the engine are not properly sealed, the engine does not operate as intended. In this respect, there have been proposed many methods.
One of the conventional methods for sealing around holes, such as a cylinder hole Hc, is shown in FIG. 2, wherein a gasket 20 comprises an upper plate 21, a lower plate 24, a middle plate 22, and a middle plate 23 having a bead 23a around a cylinder hole Hc to be sealed. The lower plate 24 is provided with a curved portion 24a located around the hole Hc, and a flange portion 24b situated above the upper plate 21. In the gasket 20, the curved portion 24a together with the bead 23a seals around the hole Hc.
When the gasket 20 is assembled, after the plates are stacked together, the curved portion 24a must be bent. In this respect, in case a hole to be sealed is small, configuration of the hole is complicated or metal quality relative to bending is not good, a curved portion may crack. If a crack is formed on the bending portion, sealing ability of the gasket decreases, and therefore the gasket can not be used any more. Therefore, the bending portion can not be employed for sealing all kinds of holes.
Also, since the sealing around the cylinder hole Hc is made by the bead 23a and the curved portion 24a, in some cases, a sufficient sealing pressure is not obtained. If the pressure in the cylinder hole Hc is too high, the gasket can not seal properly.
When the curved or bending portion is not used, a gasket 25 as shown in FIG. 3 may be used. The gasket 25 comprises an upper plate 26, a lower plate 28 and a middle plate 27 having a bead 27a around a hole Hc. In this gasket 25, the bead 27a only provides a sealing pressure around the hole Hc. Therefore, fluid passing through the hole Hc may possibly permeate through the plates. The sealing ability of the gasket 25 is not good.
In order to securely seal around a cylinder hole Hc in an engine with a cylinder liner, a gasket 30 as shown in FIG. 4 has been proposed, which was on July 4, 1986 in Japanese Utility Model Publication No. 61-105742. The gasket 30 comprises an upper plate 31 with an auxiliary bead 31a, three middle plates 32, 33, 34, and a lower plate 35 with a curved portion 35a and a flange 35b. The middle plates 32, 34 are provided with beads 32a, 34a respectively.
In the gasket 30, the auxiliary bead 31a is located above a cylindrical body of the cylinder liner and beneath the flange 35b to provisionally seal around the cylinder hole Hc, and the beads 32a, 34a are located above a flange of the cylinder liner to mainly seal around the cylinder hole Hc. In the gasket 30, different portions of the cylinder liner are sealed by the different beads.
Accordingly, one object of the present invention is to provide a steel laminate gasket, which can provide high sealing pressure around a hole to be sealed for properly sealing therearound.
Another object of the invention is to provide a steel laminate gasket as explained above, which can seal properly even in a small hole or a hole with a complicated configuration.
A further object of the invention is to provide a steel laminate gasket as explained above, in which thickness of the gasket is very thin.
A still further object of the invention is to provide a steel laminate gasket as explained above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.